Extinct New Zealand birds. Refer to the Evolutionary Ecology Research (July 2003) study of extinction in the New Zealand bird population, presented in Exercise 1.20

(p. 49). Recall that biologists measured the body mass (in grams) and type of habitat (aquatic, ground terrestrial, or aerial terrestrial) for each bird species. One objective is to compare the body mass means of birds with the three different types of habitat.

a. Identify the response variable of the study.

b. Identify the experimental units of the study.

c. Identify the factor(s) in the study.

d. Identify the treatments.